Differential pump



March 9, 1943. A. SOBEK DIFFERENTIAL PUMP Filed May 9, 19:59

Patented Mar. 9, 1943 Andre Sobck,

Paris, France; vested in the Alien Property Custodian Application May 9, 1939, Serial No. 272,665 In Luxembourg February 22, 1939 12 Claims. (01. 103- 37) The present invention relates to a liquid pump wherein it is possible to vary the discharge of the pump during rotation thereof without altering the rotating speed. The invention more particularly pertains to a liquid pump which does require a valve or valves and the operation of which may be reversed.

The liquid pump according to the invention comprises two cylinders which communicate with I each other and in which respectively move two pistons having a continuous reciprocating movement, for example respectively actuated against the action of retracting springs by twoeccentrics or cams rotating at the same speed, the periodical movements of the two pistons having a lag relatively to each other. v

Preferably, the pump is provided with a means which enables the lag between the movements of the two pistons to be varied, either while in operation, or when stopped.

A feature of the pump according to the invention is that the suction and delivery pipes open into the cylinders on the side of the pistons which in this case act as a slide valve. This arrangement enables the suction and delivery valves to be eliminated and the direction of circulation of the liquid through the pump to be reversed byvarying'the lag between the movements of the pistons.

y way of examples that are in no way limitative, various embodiments of a pump according,

to the invention, including all or part of. the

features mentioned above and furthermore exhibiting other remarkable points which also form Fig. 1 is a diagrammatical sectional view of a v pump according to the invention, of ype;

Figs. 2 and 3 are diagrams of the construction and of the operation of a pump according to the invention without a valve;

Figs. 4 and 5 are similar diagrams to those of Figs. 2 and 3 and show a'modification of construction;

Fig. 6 is a vertical section of another embodiment of a pump according to the invention;

Figs. 7 and 8 are respectively sections along the lines VII-VII and VIII-VIII of Fig. 6.

In the diagrammatical embodiment of Fig. l, the pump comprises a block I in which are arranged side by side two bores 2 and 3.01 the same diameter, which open into a common pipe 4. In said bores or cylinders 2, 3, aremounted the valve respective pistons 6, 8 driven from the end by identical eccentrics I, 8 which act on said pistons against the action of respective retracting springs 9, ill. Said eccentrics I, 8 are mounted on the same shaft il which rests in bearings I! carried by the block I andis rotated by any means. At least one of said eccentrics,'in this case the eccentric 8, is adjustably fixed on the shaft II, for example'by means of a screw [3. The opposite ends of the pipe dare respectively connected to pipes I4 and IS on which are arranged valves 16 and I! which open in opposite direction to each other. I

A kinematic consideration of .the system thus formed shows that as the movement of each piston follows a sinusoidal law, the total capacity formed by the parts of the two cylinders 2 and 3 between the pistons and the pipe 4 periodically passes through a maximum and a minimum at each revolution of the shaft ll, unless the cocentrics are set 180". out of phase relatively to each other, since in that case said capacity remains constant and the discharge is zero. When said capacity increases in volume, liquid flows from one of the pipes l4, l5 into the pipe 4 by passing through the corresponding valve l6 or 11. When the capacity decreases, liquid is driven out of the pipe linto the other pipe l4, I5 through the corresponding valve. The discharge thus obtained is ata maximum when the two eccentrics I, 8 are in phase.

It will therefore be seen that it is possible to vary the discharge oi said pump, between zero and a maximum, by setting one of the eccentrics out of phase relatively to the other. The direction of circulation of the liquid is determined by the direction of opening -oi the valves i6 and I1. J

In the modification shown in Figs. 2 and 3 the liquid inlet and outlet channels 20, 2| do not open into the pipe 4 which connects the two. cylinders 2 and 3 to each other, but each is in open communication with one of the cylinders at a point located approximately at the midstroke. positionof the piston.

pipes 20 and 2|. Furthermore the movement of the piston 6. has a lag of a little more than 180 behind that of the piston 5 and the direction of movement 01. the pistons in the position in which A kinematic consideration of the general system The pistons 5 and 6 therefore act at the same time as slide valves periodically covering and uncovering the shows that the maximum and minimum values of the capacity formed by the cylinders 2 and 3 and the pipe 4 occur at each revolution when the pistons 5 and 6 simultaneously pass through the levels N and N which are symmetrical with each other relatively to the mid-stroke of the pistons, the difference between said two levels being proportional to the lag of the movements of the pistons. In the position of the pistons shown in Fig. 2, said capacity is increasing in volume and as the pipe 20 is uncoveredwhereas the pipe 2| is covered by the piston 5, liquid passes from the pipe 20.. In Fig. 3 the pipe 2| is uncovered and the pipe 20 is covered, while said capacity is decreasing in volume so that liquid comes out of same through the pipe 2|. When the pistons reach the vicinity of the level N, the

two pipes 20 and 2| are simultaneously closed opens into the corresponding cylinder below the extreme low position of the piston and in this case the channel 25 is given a small cross-section. When the channel 20 is uncovered, suction is exerted at the same time in the channels 20 and 25 but it has little'efi'ect on the latter owing to its small cross-section, which is very much smaller than-that of the channel 20. Delivery is eiTected through the pipe 25 when the pipe 20 is covered and the capacity decreases in volume.

- The direction of circulation in this pump is consequently determined by the arrangement of the orifices and cannot be reversed. As there is no danger of water-hammering, the discharge valve 24 provided in the case of Figs. 2 and 3 is eliminated.

In the embodiment shown in Figs. 6 and 8, the eccentrics 3| and 32 which drive the pistcns'33 and 34 are fixed in an invariable position on their,

driving shaft 35 which is rotatably mounted in a casing or pump body 36. The cylinders 31 and 33 in which the pistons 33 and 34 move are formed by two parallel bores in an added part 39 which is fitted in a hole of the pump body 36 and is held in position by the pressure of a hollow plug 40 threaded in the casing 36. The suction and delivery pipes 4|, 42 extend to the Pump body 36 and open into cavities 43, 44 which are provided in the wall of the casing adjacent the part 39 and which embrace said part over a certain arc. Opposite these grooves 43, 44 respectively open two channels 45, 46 bored in the part 39, one leading to the cylinder 31, the other to the cylinder 38. Said channels 45, 46 open in this case into the cylinders in the manner as provided in Figs. 2 and 3 but they may open therein in any one of the mannersprovided in ,Figs. 1, 4- and 5.

The operation'of the pump is exactly that of the embodiment of Figs. 2 and 3 but the adjust ment'of the discharge is efiected, when stopped,

by varying the angular setting of the part 39 in the casing 36 and for that purpose it sufiices to remove the plug 40. It is obvious that by rotating this part 39, the axes of the pistons 33 and 34 are no longer arranged in the same vertical plane as the axis of the shaft 35 but are located symmetrically on either side of said plane, as shown in Fig. 8, so that a lag is produced between the movements of the two pistons.

Of course, the invention is in no way limited to the constructional details illustrated and described which have only been given by way of examples; Thus in particular the pump may be multiple, that is to say comprise more than one group of two pistons co-operating with each other. Similarly the actuating cams or eccentrics may be replaced by a connecting rod and crank drive.

What I claim is:

l. A liquid pump of minute output comprising two cylinders in communication with each other. at least one of said cylinders being mounted to rotate about an axis parallel with its own axis, means for securing said last named cylinder in any desired position, inlet and outlet means to and from said cylinders. two pistons respectively movable within said cylinders, spring means urging said pistons in one direction and rotary eccentric or cam means for actuating said pistons against said springs whereby to impart to said pistons reciprocal motions of the same period but having a lag relatively to each other.

2. A liquid pump of minute output including a body, provided with a hole, a part mounted in said hole to rotate about an axis, two cylinders formed by bores in said part, said bores being substantially parallel with said axis, a removable hollow plug fitted in said hole and "holding said part in position, said cylinders being in communication through the inner part of said hollow plug, inlet and outlet means to and from said cylinders, two pistons respectively movable within said cylinders, spring means urging said pistons in one direction, eccentric or cam means, rotating about an axis substantially at right angle with said axis and actuating said pistons against said spring means whereby to impart to said pistons reciprocal motions having a lag relatively to each other.

3. A liquid pump as claimed in claim 1 in which at least the inlet means opens in a cylinder at a point situated approximately midway of the stroke of the associated piston.

4. A liquid pump as claimed in claim 2 in which, in order to form said inlet and outlet means, the said part is provided with ports leading to the respective cylinders, corresponding suction and delivery pipes carried by the body, each group of corresponding pipe and port leading to a cavity provided between said hole and said part and embracing said latter over a certain arc.

5. A liquid pump as claimed in -claim 1 in which said inlet means opens in one cylinder at a point situated approximately midway of the piston stroke while said outlet means opens in the other cylinder at a point also situated approximately midway of the piston stroke, both said pistons being arranged to cooperate with said inlet and outlet means as a slide-valve.

6. A liquid pump of minute output comprising two cylinders in communication with each other,.

situated approximately midway of the piston stroke and the associated piston is arranged to cooperate with said inlet means as a slide valve.

7. A liquid pump as claimed in claim 6 in which said outlet means opens in the other cylinder at a point also situated substantially midrotate about an axis substantially parallel with its own axis and distant from same, meansifor securing said cylinder in any desired position,

inlet and outlet means to and from said cylinders, -two pistons reciprocally mounted within said cylinders and means for reciprocating said pistons.

9. A liquid pump of minute output comprising two cylinders in communication with each other, at least one of said cylinders being mounted to rotate about an axis substantially parallel with its own axis and distant from same, means for securing said cylinder in any desired position,

inlet and outlet means to and from said cylinders, two pistons reciprocally mounted within said cylinders, an operating excentric or cam for each of said pistons rotating about an axis substantially perpendicular to the axis of the corresponding cylinder, and driving means rotating said excentrics or cams. I i

10. A, liquid pump as claimed in claim 8, in which both cylinders are substantially parallel and are mounted to rotate together about a single axis substantially parallel with their own axis. 7

11. A liquid pump as claimed in claim 9, in which said two cylinders are parallel and mounted to rotate together about an axis parallel with their own axis, and in which the said driving means includes a common driving shaft on which said excentrics or cams are mounted.

12. A liquid pump as claimed in claim 1, in which the eccentric or cam means is mounted on a driving shaft arranged substantially perpendicular to said axis and directly engaging the associated pistons.

ANDRE SOBEKr 

